---
title: Call Tools in Parallel
description: Learn to call tools in parallel using the Vercel AI SDK in your Next.js App Router application
---

# Call Tools in Parallel

Some language models support calling tools in parallel. This is particularly useful when multiple tools are independent of each other and can be executed in parallel during the same generation step.

<Browser>
  <ChatGeneration
    history={[
      { role: 'User', content: 'How is it going?' },
      { role: 'Assistant', content: 'All good, how may I help you?' },
    ]}
    inputMessage={{
      role: 'User',
      content: 'What is the weather in Paris and New York?',
    }}
    outputMessage={{
      role: 'Assistant',
      content:
        'The weather is 24°C in New York and 25°C in Paris. It is sunny in both cities.',
    }}
  />
</Browser>

## Client

Let's modify our previous example to call `getWeather` tool for multiple cities in parallel.

```tsx filename='app/page.tsx'
'use client';

import { useState } from 'react';
import { Message, continueConversation } from './actions';

// Force the page to be dynamic and allow streaming responses up to 30 seconds
export const dynamic = 'force-dynamic';
export const maxDuration = 30;

export default function Home() {
  const [conversation, setConversation] = useState<Message[]>([]);
  const [input, setInput] = useState<string>('');

  return (
    <div>
      <div>
        {conversation.map((message, index) => (
          <div key={index}>
            {message.role}: {message.content}
          </div>
        ))}
      </div>

      <div>
        <input
          type="text"
          value={input}
          onChange={event => {
            setInput(event.target.value);
          }}
        />
        <button
          onClick={async () => {
            const { messages } = await continueConversation([
              ...conversation,
              { role: 'user', content: input },
            ]);

            setConversation(messages);
          }}
        >
          Send Message
        </button>
      </div>
    </div>
  );
}
```

## Server

Let's update the tools object to now use the `getWeather` function instead.

```ts filename='app/actions.ts'
'use server';

import { generateText } from 'ai';
import { openai } from '@ai-sdk/openai';
import { z } from 'zod';

export interface Message {
  role: 'user' | 'assistant';
  content: string;
}

function getWeather({ city, unit }) {
  // This function would normally make an
  // API request to get the weather.

  return { value: 25, description: 'Sunny' };
}

export async function continueConversation(history: Message[]) {
  'use server';

  const { text, toolResults } = await generateText({
    model: openai('gpt-3.5-turbo'),
    system: 'You are a friendly weather assistant!',
    messages: history,
    tools: {
      getWeather: {
        description: 'Get the weather for a location',
        parameters: z.object({
          city: z.string().describe('The city to get the weather for'),
          unit: z
            .enum(['C', 'F'])
            .describe('The unit to display the temperature in'),
        }),
        execute: async ({ city, unit }) => {
          const weather = getWeather({ city, unit });
          return `It is currently 25°${weather.value} and ${weather.description} in ${city}!`;
        },
      },
    },
  });

  return {
    messages: [
      ...history,
      {
        role: 'assistant' as const,
        content:
          text || toolResults.map(toolResult => toolResult.result).join('\n'),
      },
    ],
  };
}
```
